PARADISE, Butte County — More than 30,000 people fled for their lives Thursday as a late-season wildfire swept across this town in the Sierra foothills, incinerating numerous homes and businesses and prompting desperate rescues of residents trapped inside buildings and on clogged evacuation routes.

The blaze exploded to more than 20,000 acres, adding to a catastrophic two years of wildfires in California that have raised new questions about how the state will cope with a warmer and drier climate.

Smoke turned the daytime sky black in Paradise, a community of 27,000 that sits 15 miles east of Chico and 80 miles north of Sacramento. Authorities raced to evacuate a hospital while calling in hundreds of crews from across the region to attack the flames from the ground and by air.

“There’s pretty much complete devastation in that community — entire streets where houses are wiped out,” said Lynne Tolmachoff, spokeswoman for the California Department of Forestry and Fire Protection. “It’s not looking very good at all.”

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Video clips from Camp Fire, wildfire growing rapidly in Butte County, California on Thursday, Nov. 8, 2018. Thousands of people were ordered to evacuate several Sierra foothills towns near Chico as a wildfire raged out of control.

Media: SFGATE

As of Thursday evening, the Camp Fire had no containment, and 15,000 structures were threatened. The flames moved within 2 miles of Chico city limits, and around 9 p.m., residents in the southern part of the city were advised to evacuate.

High winds were hampering air tankers’ efforts to extinguish the flames, said Cal Fire spokesman Scott McLean. Similar winds were expected to continue through the night. Red-flag conditions were in place until at least 10 a.m. Friday.

Fire officials said they had received reports of some deaths from the blaze. At least two firefighters were injured. Several hundred homes, and perhaps more than 1,000, had burned.

“We were engulfed in flames,” said Butte County Supervisor Doug Teeter. “I don’t know what we are coming back to after this. Probably a moonscape. As we drove out, homes were burnt to the ground.”

Among the structures lost to the flames were a McDonald’s, a Mormon church, a Black Bear Diner and Paradise’s wood welcome sign. Streams of residents hurried out of town, inching along the few available routes.

Family members and friends searched for scores of missing people. They inundated 911 with hundreds of requests for help tracking down people who were feared trapped behind fire lines. They flooded Twitter too, posting names and photos of loved ones, along with the addresses where they’d last been seen.

The cause of the fire, which ignited at 6:30 a.m., was under investigation. Authorities released no immediate information about the extent of the damage and the toll of injuries. The inferno was so huge that dense smoke clogged skies throughout the Bay Area — roughly 200 miles southwest of the blaze — and residents across Northern California were warned to expect poor air quality through Friday.

Evacuation efforts were “difficult, to say the least,” said Lt. Al Smith of the Butte County Sheriff’s Office, noting that several deputies who ventured into evacuation zones to rescue residents also became trapped by flames burning around them. “I can’t think of an area that’s safe right now.”

A fire crew keeps an eye on the Camp FireMedia: San Francisco Chronicle

The Camp Fire burns in a Paradise neighborhoodMedia: Gabrielle Lurie

A home in Paradise burns during the Camp FireMedia: Gabrielle Lurie

A home in Paradise California burns during the Camp FireMedia: Gabrielle Lurie

Which Respirator Masks Protect Against Smoke?Media: San Francisco Chronicle

Safeway Grocery in ParadiseMedia: Scott Strazzante

Paradise Elementary SchoolMedia: Scott Strazzante

Camp FireMedia: Gabrielle Lurie

The Camp Fire burns in Paradise on Nov. 8, 2018.

Media: San Francisco Chronicle

The blaze, named the Camp Fire because of its proximity to Camp Creek Road near Highway 70 in the Feather River Canyon, was scorching several areas within Paradise, which is home to many retirees. Acting Gov. Gavin Newsom, filling in while Gov. Jerry Brown traveled out of state, declared a state of emergency in Butte County.

The Butte County towns of Paradise, Pulga and Concow were evacuated shortly after the fire started. Cal Fire officials said residents of Magalia, Butte Creek Canyon and Butte Valley had also been ordered to leave.

Pacific Gas and Electric Co. reported that 34,280 customers in Butte County and neighboring Plumas County had lost power.

Firefighters spent the morning trying to evacuate trapped Paradise residents while creating firebreaks within the town and even moving some people to empty parking lots. Engines from the San Francisco and Santa Rosa fire departments and other California agencies were aiding Butte County firefighters.

The Paradise Unified School District and Butte College closed their doors Thursday morning under evacuation orders from fire officials. The Paradise schools superintendent said she had seen photos of several schools burning.

Feather River Hospital in Paradise was evacuated after flames jumped a road leading to the hospital. Fire officials said some people were trapped in a tunnel under the hospital and forced to shelter in place before escaping. The hospital largely survived, but an auxiliary building burned, according to Cal Fire.

“In the past few years, just the way fires have moved, firefighters have had to help with evacuations before they can go back in to put out the fire,” Tolmachoff said.

Butte County officials did not send an Amber Alert-style message to warn people in and around Paradise about the rapidly spreading fire early Thursday, a Sheriff’s Department spokeswoman said. Instead, the department turned to an opt-in program to contact an estimated 23,000 people who had signed up to receive emergency notifications or who had landline telephones.

In October 2017, Sonoma County officials opted not to send out the Amber Alert-style message during the Tubbs Fire, which eventually killed 24 people. That decision was criticized later in a state audit.

In Paradise on Thursday morning, Jennifer Broussard, 41, woke to thunder — or at least that’s what the fire sounded like, she said.

She and her husband, Ryan, 50, left their home in a rush. Both in their pajamas, they had no time to change into anything else. Police were everywhere shouting, “Move! Go! Get out!”

She moved from Los Angeles to Paradise 20 years ago, and was surprised upon arriving in town how clear the stars were at night. But in the daytime Thursday, she couldn’t see anything except black smoke obscuring the sun and sky.

“The simple things we take for granted,” Broussard said at an evacuation shelter in Oroville. She tapped ash from her cigarette on the concrete and said, “That is a whole town gone.”

The intensity of the Camp Fire’s surge through Paradise drew immediate comparisons to the Tubbs Fire, which wiped out whole neighborhoods in and around Santa Rosa, and the Carr Fire, which blitzed Redding this year. Gov. Brown and others have raised alarm about the nearly year-round danger in the state, but no broad solutions have surfaced. Twice in the past two years, fires have set the state record for size.

In the tiny town of Concow, northeast of Paradise, Nate Tockey, 35, got a call from a neighbor at 7 a.m. warning him about the fire. He woke his three children, warned his wife and saw a dark, orange sky when he went to the porch.

His wife, Kat Tockey, 36, left her purse behind, and they didn’t bother to grab their computer or important papers from a filing cabinet. By the time the five of them piled into a car, 50- to 100-foot flames were approaching from three sides. They could feel the heat through the closed windows of their sport utility vehicle.

“At this point I’m pretty sure the house is gone. I’m prepared for the worst,” Nate Tockey said. “We knew we lived in an area of fire danger, but we never knew it would be like that.”

Kat Tockey and the children — 9-month-old and 11-year-old sons and an 8-year-old daughter — were staying at the Neighborhood Church evacuation center in Chico. Pets weren’t allowed, so Nate Tockey said he would sleep in the car with their rottweiler, Tig, and cat, Kitsy.

Kendra Luck evacuated with her father and stepmother a few hours after the fire started. Her stepmother spotted flames shooting up a hillside outside of town around 8 a.m., and the three of them started packing.

An hour later, the smoke was so dense that they turned lights on in the house. The sky was an eerie — but familiar — red glow. Her father and stepmother have lived in the same house in Paradise for 16 years, and this was their third fire evacuation.

“They’re getting used to this,” said Luck, a former Chronicle photographer. “Everything was glowing that fire red. That was enough for them, so we just packed up and left.”

Photo: Todd Trumbull

Hundreds of people were unaccounted for Thursday evening after the mad rush to evacuate. Especially worrisome were reports of older people — including some with dementia or mobility problems — who had not checked in with friends or relatives.

A 96-year-old woman who slipped into a stranger’s car to flee from her retirement home as it was engulfed early Thursday was among the missing. Marcia Hamilton, who had been living at Feather Canyon Retirement Community for nine years, was evacuated from the senior home around 9:30 a.m., just as walls of fire closed in.

She joined dozens of other residents outside the main entrance waiting for rides out of town, but firefighters, staffers and others were scrambling to find transportation, said Hamilton’s daughter, Lynn Hamilton. Her mother was put in a car with strangers who said they would take her to an evacuation center. But Lynn Hamilton never heard whether they arrived.

She was worried in part because her mother left without medication required for her heart condition and cholesterol, and without her walker or a cell phone.

“She needs to take her medication every day,” Lynn Hamilton said.

Marcia Hamilton was found hours later in Yuba City, 50 miles to the south.